We are studying the protein kinases (and phosphatases) present in skeletal muscle and heart, their mechanisms of control, substrate specificity and physiological effects resulting from the phosphorylation of their substrate proteins. This project includes these aspects: 1) Identification of proteins phosphorylated. 2) Characterization of the protein kinases catalyzing the phosphorylation, ion, and also the characterization of the phosphatases reversing these phosphorylations. 3) Study of the mechanisms of control of the activity of the protein kinases, and 4) possible physiological results of the phosphorylation of the protein substrates.